Problèmes de fonctions CD audio
La partie inscriptible d'un CD audio est une cou-
ronne de rayons 25 et 55 mm. Un faisceau laser
55 mm 25 mm
lit la musique en allant de l'intérieur de cette
couronne vers l'extérieur.
On note r la distance en millimètre du laser au
bord du cercle intérieur après lecture d'une par-
tie de la musique.
1. À quel intervalle I appartient r?
2. (a) Justifier que l'aire S(x) de la couronne de largeur z est égale à S(x) = 7(25+x)2-pi x 252.
En déduire que, pour tout x € I, S.2) = ?? +5073
(b) Calculer S(0) : ce résultat est-il prévisible?
(c) Montrer que S(30) = 24007 et interpréter le résultat.
3. D'un bord de la couronne à l'autre, le CD contient 80 min de musique. Sachant que la durée
en minute de lecture audio D(x) est proportionnelle à l'aire S(x), on peut montrer que,
S(2) 1
pour tout x € [0;30), D(x) = 80 x
(x2 + 50x).

351°f

step-by-step explanation:

2 & 7

step-by-step explanation:

he climbs 300 ft/hr at a constant rate. the peak is at 1,500 ft.

when going up, he reaches 600 ft in 2 hours. remember, that he is going in a constant rate. divide 600 with 300:

600/300 = 2

assuming that he takes the same route back (meaning that it's a 1500 ft route back, you can solve.

note also that you are solving when he gets back to 600 ft after he reaches the peak.

first, find the amount of hours it takes to get up the peak. divide the total amount (1500), with the ft/her (300) to get the amount of hours (x):

1500/300 = x

x = 5

it takes jamie 5 hours to get up. now, he is returning down, and reaches 600 (his current destination). remember that he climbs at a constant 300 ft/hr. divide 600 with 300:

600/300 = x

x = 2

now add the two numbers together.

x = 5 + 2 = 7

jamie takes 7 hours to go up the mountain and reach his current position when descending.

(total amount/constant rate) = (time).

remember that it is a constant rate, so in total, when he gets back down the mountain, it will take the same amount of time as when he goes up. the total amount for the round trip is: 5 + 5 = 10.

~

abby has a greater debt becasue she owea 5 more then alan does